In recent years, a user terminal (so-called dual terminal) including a cellular communication unit and a wireless LAN (WLAN) communication unit becomes widely available. Further, the number of WLAN access points (hereinafter simply referred to as an “access point”) managed by an operator of a cellular communication system increases.
Therefore, in 3GPP (3rd Generation Partnership Project) which is a project aiming to standardize a cellular communication system, it is planned to consider a technology capable of strengthening cooperation between a cellular communication system and a WLAN system (see Non Patent Literature 1).
For example, a method may be considered where a traffic exchanged between the user terminal and the cellular base station is transitioned to the WLAN system (that is, offloaded) so as to disperse a traffic load in the cellular base station to the WLAN system.